1. FIELD OF THE INVENTION
The present invention relates to a vehicular soundproof structure which is applicable to the surfaces of panels forming a vehicle body or chassis.
2. DESCRIPTION OF THE PRIOR ART
Various kinds of soundproof structures have conventionally been proposed with an effort to alleviate noises and vibrations which are generated by an engine and other components on the body of a vehicle and come into a vehicle compartment.
As such conventional soundproof structure, Japanese patent application laid-open No. 18538/1986 has made known, for example, the structure consisting of a viscous foamed material layer for sound absorption use, a restricting layer formed of a flexible material such as aluminum foil or rubber sheet, a sound absorbing layer and a skin layer which are laminated in the mentioned order from lower to upper sides on the surface portion of a vehicle body forming panel.
However, the structure known from said Japanese publication requires the step of impregnating the foamed material with a viscous material such as asphalt to provide the viscous foamed material layer, which undesirably increases the number of production steps and the kind of materials used by addition of such viscous material. Moreover, workers must pay attention to handling the viscous material such as asphalt in order to avoid its adhesion to their clothes. Thus, the conventional structure suffers from a problem that its handling is quite laborious.